Spire will develop a new X-ray detector by monolithically integrating photodiodes on ceramic scintillators for X-ray computed tomography (XCT). The proposed detector will have a CdTe/CdS photodiode fabricated directly on the scintillator instead of the mechanically stacked Si photodiodes in current use. Reduced optical loss at the photodiode/scintillator interface and a better spectral match to the scintillator emission wavelength will improve performance over conventional detectors. The new detector will reduce assembly complexity by obviating the need for precise stacking of photodiodes on the scintillator. In Phase I, we will demonstrate a single-element integrated X-ray detector with improved signal. CdTe/CdS photodiode structures will be deposited directly on the scintillator by a low-cost thermal evaporation technique. The detector will be tested using a diagnostic X-ray source. During Phase II, we will design and fabricate a detector array and determine the potential of these integrated X-ray detectors for X-ray computed tomography. Spire will work closely with XCT manufacturers and end users toward commercialization of this technology.